Process for producing improved rayon threads from viscose and the rayon threads produced thereby



United States Patent ()fifice 3,377,179 Patented Apr. 9, 1968 3,377,179 PROCESS FOR PRODUCING IMPROVED RAYON THREADS FROM VISCOSE AND THE RAYON THREADS PRODUCED THEREBY Adriaan C. Cranendonk, Velp, Gelderland, Netherlands, assignor to American Enlra Corporation, Enka, N.C., a corporation of Delaware No Drawing. Filed June 6, 1966, Ser. No. 555,237 Claims priority, application Netherlands, June 12, 1965,

65-7,541 6 Claims. (Cl. 106165) ABSTRACT OF THE DISCLOSURE A process for producing rayon threads from viscose which includes the steps of spinning viscose containing not greater than 0.04% by weight, based on the weight of the viscose, of at least one aliphatic ether that contains from 8 to 20 carbon atoms, is liquid at 20 C., is miscible with carbon disulfide, is practically immiscible with water, and has a boiling point higher than that of carbon disulfide, into an acidic spinning bath to produce spinning filaments therein, forming thread from the spinning filaments within said bath and drawing the resulting thread from the bath, thereby obtaining thread having a glossy appearance and preventing the formation of large gas bubbles within the spinning filaments.

Specification This invention relates to a process for producing rayon threads by spinning viscose into a spinning bath and to the rayon threads produced thereby. In particular, this invention relates to a process in which viscose containing certain ethers is spun in a spinning bath to form improved rayon threads (or yarns), to the rayon threads per se, and to the rayon staple fibers and fabrics made from the threads.

In the production of rayon threads viscose is extruded through a spinning nozzle into a spinning bath which contains sulfuric acid as well as certain salts. Thereafter, the freshly formed rayon threads are stretched and wound. The salts most commonly used in a spinning bath are sodium sulfate, magnesium sulfate, zinc sulfate and ammonium sulfate. The spinning bath and/or the viscose may also contain additional spinning aids; for instance, cation-active substances.

Unexpectedly, gas bubbles may form in the filaments passing through the spinning bath at some distance from the spinning nozzle. The gas bubble grows as it presses the viscose present in the superficially coagulated filament back to the spinning nozzle. The length of the gas bubble may vary from 1 to 100 mm. Usually, the pressure created by such a gas bubble causes a weak wall of the filament to burst locally. Consequently a hollow portion or part is formed in the filament.

When threads composed of filaments that are hollow in various portions are dried, the hollow portions may locally be compressed. As a result, the fabric into which these threads are woven show the Well-known bright spots at those places where the hollow portions have been compressed.

The reason for the formation of a gas bubble in a spinning filament is unknown. The phenomenon occurs quite unexpectedly and without apparent cause. Heretofore, it has been found that the formation of gas bubbles is promoted by an increase in the spinning bath temperature as well as by an increase in the resin content of the cellulose from which the viscose is to be prepared.

Furthermore, a process is known for manufacturing rayon threads and rayon staple fibers from viscose which obviates the formation of large gas bubbles in the filaments. This process is carried out so that the viscose to be spun contains a saturated aliphatic hydrocarbon, a saturated alicyclic hydrocarbon, a mononuclear aromatic hydrocarbon or a mixture thereof. The hydrocarbons must contain at least six carbon atoms, be liquid at 20 C., be miscible with carbon disulfide, be practically immiscible with water, and have a boiling point higher than that of carbon disulfide. In addition, the hydrocarbons are to be present in the viscose in an amount not higher than 0.04% by weight, based on the weight of the viscose.

One disadvantage of these hydrocarbons in the viscose is that they show a high solvent action on various substances.

For example, prior to being spun, viscose is filtered by means of filter presses. These filter presses are painted and covered with cloth. Use is often made of cloth produced from polyvinyl chloride threads.

In filtering a viscose containing the afore-mentioned hydrocarbons, the paint and the polyvinyl chloride cloth of the filter presses are dissolved. The hydrocarbons also attack the paint on the inside surfaces of the containers in which the viscose is stored.

Advantageously, in accordance with this invention, a process has now been found in which the formation of large gas bubbles in the spinning filaments at any time may be prevented and in which there is substantially no chance of dissolving the paint and the polyvinyl chloride cloth of the filter presses.

This invention thus contemplates a process for producing rayon threads from viscose which comprises spinning viscose that contains a small amount of at least one selected aliphatic ether into an acidic spinning bath to produce spinning filaments therein, forming thread from said spinning filaments within said bath and drawing the resulting thread from the bath; the ether in the viscose allowing the resulting thread to have a glossy appearance and preventing the formation of large gas bubbles within the spinning filaments.

In particular, this invention is directed to a process for producing rayon threads in which viscose containing one or more liquid aliphatic ethers is spun into a spinning bath containing sulfuric acid and its salts to form threads therein, and the resulting threads are removed from the bath and stretched; said aliphatic ethers containing from 8 to 20 carbon atoms, being liquid at 20 C., being miscible with carbon disulfide, being practically immiscible with water, having a boiling point higher than that of carbon disulfide, and being present in the viscose in an amount not higher than 0.04% by Weight based on the weight of the viscose.

In addition, this invention is also concerned with the improved rayon threads produced from the ether-containing viscose which have a glossy appearance and which can be Woven into fabrics substantially free of bright spots, gs-Well as with staple fibers and fabrics obtained there- Since the viscose used in accordance with this invention contains only a small amount of the liquid ethers, the appearance of the resulting thread is not influenced. It might be expected, however, that the presence of these liquids would give the threads a dull appearance, because it is known that the presence of ethers and other organic solvents in viscose in a larger amount, e.g., 0.5 to 10% by weight, results in dull (white) threads. In that case, the dullness (whiteness) of the threads apparently is caused by the filaments being internally and superficially porous as a result of gas being formed therein.

Immediately after spinning, threads produced from viscose containing a large amount of ether are not very white because there is still a small amount of ether inside 3 the filaments at this stage. After a short time, the ether evaporates and the threads assume a whiter appearance.

The component filaments of the threads obtained by the process of this invention, however, are not at all porous and have a lustrous appearance. The single component filaments further show a higher strength than those filaments having voids which are spun from the viscose lots that do not contain the liquid ethers in the prescribed amount.

The aliphatic ethers useful for the purposes of this invention, as previously mentioned, include those ethers containing from 8 to carbon atoms. Exemplary of these ethers are: butyl isobutyl ether, propyl isoamyl ether, dibutyl ether, di sec butyl ether, diisobutyl ether, ethyl hexyl ether, methyl heptyl ether, butyl isoamyl ether, dipentyl ether, ethyl octyl ether, diheptyl ether, octyl hexyl ether, dioctyl ether, ethyl cetyl ether, octyl decyl ether, heptyl dodecyl ether, didecyl ether, and the like.

In order to obtain rayon threads having a lustrous and glossy appearance, the amount of aliphatic ether added to the viscose must be no greater than 0.04% by weight of the Weight of the viscose. In general, a particularly effective working range for the ethers extends from about 0.01 to about 0.04% by weight based on the viscose. Higher amounts, e.g., 0.06 to 0.1% and above also have been found to prevent the formation of large gas bubbles in the spinning filaments. However, the resulting threads have a dull appearance and therefore are not suitable for the purposes of this invention.

The spinning baths employed by the process of this invention contain sulfuric acid and certain of its salts, e.g., sodium sulfate, magnesium sulfate, zinc sulfate and the like in various weight proportions. Also, different detergents including lauryl pyridinium chloride and the like may be present in the spinning bath.

It will be appreciated that use of the ethers in the process of this invention allows various apparatus to be used for preparation and spinning of viscose without causing substantial dissolving of paints, polymeric filters and the like. It will be also appreciated that an additional advantage obtained by using the ethers is that upon dcaeration of the viscose prior to spinning, the foam formed at the surface quickly breaks up.

Furthermore, it will also be appreciated that the addition of the liquid ethers contemplated by this invention may take place in any stage of the preparation of viscose. For instance, the ethers may be added to the alkali cellulose, or they may be added to the viscose after its preparation. Also, the ethers may be injected into the spinning conduit through which the viscose is passed to the spinning machine.

The process of this invention and the rayon threads produced thereby are further described with reference to the following examples which are intended to be merely illustrative and not to be limitative of the scope of the invention.

Example I A viscose was prepared from alkali cellulose which was xanthated with 32% by weight of carbon disulfide, based on the cellulose in the alkali cellulose. The viscose, which had a Hottenroth maturity index of about 6 and a viscosity at 20 C. of 33 seconds (Ball Fall Method) was spun through a spinning nozzle with 18 orifices into a spinning bath at 55 C. The bath contained 7% by weight of sulfuric acid, 17% by weight of sodium sulfate, 4% by weight of magnesium sulfate, 3% by weight of zinc sulfate, and 40 milligrams per liter of laurylpyridinium chloride.

A freshly formed thread with a tex of 8 was drawn from the spinning bath at a rate of 60 meters per minute, and stretched by in the air. The rate at which the thread was fed into a rotating spinning pot was 75 meters per minute.

While passing through the spinning bath, the spinning filaments showed long gas bubbles which caused the filaments locally to burst so that hollow portions or parts were formed in the filaments.

Subsequently, the following aliphatic ethers were successively injected into the viscose passing through the spinning conduit to the spinning machine: butyl isobutyl ether, propyl isoamyl ether, dibutyl ether, di sec butyl ether, diisobutyl ether, ethyl hexyl ether, methyl heptyl ether, butyl isoamyl ether, dipentyl ether, ethyl octyl ether, diheptyl ether, octyl hexyl ether, dioctyl ether, ethyl cetyl ether, octyl decyl ether, heptyl dodecyl ether, didecyl ether; each in amounts of 0.01% by weight, 0.02% by weight, 0.04% by weight, 0.06% by weight, and 0.1% by weight, based on the weight of the viscose.

By injecting the ethers in amounts of 0.01% by weight, 0.02% by weight, and 0.04% by weight, the formation of long gas bubbles was prevented in the filaments. The filaments further did not contain small voids and showed smooth surfaces. As a result, the threads had a normal glossy appearance.

By injecting the ethers in higher percentages (0.06% by weight and 0.1% by weight) the formation of long gas bubbles was also prevented in the filaments. However, the filaments contained numerous microscopically minute voids and had porous surfaces. As a result, the threads were dull.

The remainder of the viscose was divided into several lots (1 to 15). Various amounts of different aliphatic ethers were added to the viscose lots and then the viscose lots were spun in the same manner as the initial viscose.

In the spinning of the viscose lots 1, 2, 4, 5, 7, 8, 10, 11, 13 and 14, no long gas bubbles were formed in the filaments. As shown in Table 1 below, the filaments further contained no voids and had smooth surfaces. As a result, the threads had a normal glossy appearance.

In the spinning of the viscose lots 3, 6, 9, 12 and 15, which contained a higher percentage (0.06% by weight) of the various ethers, there also was no formation in the filaments of long gas bubbles. However, these filaments contained many microscopically minute voids and had porous surfaces. As a result, the threads were dull. These results are tabulated below:

TABLE I Amount 01' Appearance Viscose Ether added Ether added of Resulting Lot in percent Threads by weight 0.02 Dibutyl ether Glossy. do Do. do Dull.

Diisobutyl ether. Glossy. do 0.

0. 02 Didccyl ethe 0. 06 .....do Dull.

Example 11 In this example, alkali cellulose similar to that used in Example I was divided into several lots (1 to 10) and viscose lots were prepared and spun into threads in the same manner described in Example I.

To the lots 1 and 2 dibutyl ether was added in such amounts that the viscose lots prepared therefrom contained 0.04% by weight, and 0.06% by Wcightof dibutyl ether, respectively.

To the lots 3 and 4 diisobutyl ether was added in such amounts that the viscose lots prepared therefrom contained 0.04% by weight, and 0.06% by weight of diisobutyl ether, respectively.

To the lots 5 and 6 dipentyl ether was added in such amounts that the viscose lots prepared therefrom contnined 0.04% by weight and 0.06% ether, respectively.

To the lots 7 and 8, diheptyl ether was added in such amounts that the viscose lots prepared therefrom contained 0.04% by weight, and 0.06% by weight of diheptyl ether, respectively.

To the lots 9 and 10, didecyl ether was added in such amounts that the viscose lots prepared therefrom contained 0.04% by weight, and 0.06% by weight of didecyl ether, respectively.

In the spinning of the viscose lots prepared from the alkali cellulose lots 1, 3, 5, 7 and 9 (containing 0.04% by weight of the aliphatic ethers) no long gas bubbles were formed in the filaments.

The resulting filaments did not contain minute voids and had smooth surfaces. The threads had a glossy appearance.

Also in the spinning of the viscose lots from the alkali celulose lots 2, 4, 6, 8, and 10, which contained a higher percentage (0.06% by weight) of the ethers, no long gas bubbles were formed in the filaments. However, the resulting filaments did contain microscopically minute voids and had porous surfaces. As a result, the threads had a dull appearance.

by weight of dipentyl Example III In this example, the procedures used in Example II were repeated with the exception that the ethers were added to the Xanthated alkali cellulose instead of to the alkali cellulose.

The results obtained were the same as those described in the experiments of Example II.

It will be understood that while the novel features of this invention are described in the specification and examples and are pointed out in the appended claims, ous modifications and variations may be made in the features described by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

vari- 1. A process for producing rayon threads from viscose which comprises spinning viscose that contains from about 0.01 to about 0.04%, by weight, based on the weight of the viscose of an aliphatic ether, into an acidic spinning bath to produce spinning filaments therein, forming thread from said spinning filaments Within said bath and drawing the resulting thread from the bath, the ether in the viscose being selected from the group consisting of butyl isobutyl ether, propyl isoamyl ether, dibutyl ether, di-sec-butyl ether, diisobutyl ether, ethyl hexyl ether, methyl heptyl ether, butyl isoamyl ether, dipentyl ether, ethyl octyl ether, diheptyl ether, octyl hexyl ether, dioctyl ether, ethyl cetyl ether, octyl decyl ether, heptyl dodecyl ether and didecyl ether allowing the resulting thread to have a glossy appearance and preventing the formation of large gas bubbles within the spinning filaments.

2. The process of claim 1 in which said spinning bath contains sulfuric acid and certain of its salts.

3. The process of claim 1 which further comprises cutting the resulting threads into staple fibers.

4. A staple fiber produced by the process of claim 3.

5. An improved rayon thread produced by the process of claim 1.

6. A fabric made from the thread of claim 5 which is substantially free of bright spots.

References Cited UNITED STATES PATENTS 2,393,817 1/1946 Schlosser 106165 2,481,693 9/1949 Schlosser 106-165 2,489,310 11/1949 Moss 106165 Re. 24,486 6/ 1958 Mitchel 106-165 2,040,712 5/1936 Robertson 106-165 3,047,412 7/ 1962 Wolfe 106-165 FOREIGN PATENTS 588,698 11/1933 Germany.

JULIUS FROME, Primary Examiner. 

